 Back to the Fat Days Fractal Index L-systems were originally introduced in the study of formal languages and were used as mathematical models of plant development. A deterministic L-system consists of an alphabet of letters, an initial word called the axiom, and a set of production rules that tell how to update the word from one iteration to the next. The graphical implementation of an L-system is based on turtle graphics, in which a point (the turtle) is given directions for moving around the plane. For example, in FractInt, the letter "F" is interpreted as a direction to move forward one step while drawing a line, and "+" is a command to turn counterclockwise 360/Angle degrees. More information about how to create an L-system with FractInt is available in FractInt's online help. The images below are thumbnails of higher resolution images that I created with FractInt. To view them in their full glory, follow these steps: Download FractInt Download marston.l, a text file containing the instructions for drawing the L-systems pictured below. Install FractInt and put marston.l in your FractInt directory. Run FractInt and choose the lsystem fractal type. Hit F6 to open marston.l. ```Angle 12 Axiom -F++F[++F]--F[++F]--F[++F]--F[++F]--F[++F]--F F=F[++F----F]--F++++F--F``` ```Angle 8 Axiom F[+F[+F]--F]-F[-F]++F-F F=F[+F[+F]--F]-F[-F]++F-F``` ```Angle 8 Axiom +F--F--F--F F=F[+F[+F]--F]-F[-F]++F-F``` ```Angle 40 Axiom ++[F]++++++++[F]++++++++[F]++++++++[F]++++++++[F] F=F[+++++F----------F]-----F++++++++++F-----F``` ```Angle 40 Axiom ++[F]++++++++[F]++++++++[F]++++++++[F]++++++++[F] F=F[+++++FF----------FF]-----FF++++++++++FF-----F``` Brian Marston